1. Technical Field
The present invention relates to an illuminator and a projector.
2. Related Art
There has been a known illuminator including a light source that emits light, a first lens array formed of a plurality of first lenslets, a second lens array formed of a plurality of second lenslets corresponding to the plurality of first lenslets, a polarization conversion element that converts light fluxes from the second lens array into polarized light fluxes and outputs them, and a superimposing lens that superimposes sub-light fluxes from the polarization conversion element on one another (see International Publication No. 97/50012, for example). The first lens array, the second lens array, and the superimposing lens form alight homogenizing system that homogenizes the in-plane optical intensity distribution of the light (what is called lens integrator system).
In the illuminator of related art, the plurality of first lenslets and the plurality of second lenslets are each arranged in a matrix (also called row-column matrix). The polarization conversion element is formed of a plurality of columns of polarization conversion units that convert light fluxes from the plurality of second lenslets into polarized light fluxes on a column basis. Further, the number of columns of the first lenslets and the number of columns of the second lenslets are the same as the number of columns of the polarization conversion units.
The illuminator of related art, which includes the lens integrator system and the polarization conversion element, can output polarized light having a homogenized in-plane optical intensity distribution and hence can be suitably used with an apparatus using “polarized light having a homogenized in-plane optical intensity distribution” (such as liquid crystal apparatus).
In a technical field of illuminators, an illuminator is always required to use light more and more efficiently, which holds true for the illuminator including the lens integrator system and the polarization conversion element described above.